1. Field of the Invention
The present invention relates generally to computer systems and specifically to transmitting video and/or audio signals between a human interface and a computer in a system of co-located computer systems over a transmission medium, for example, in a videoconferencing system.
2. Description of the Related Art
The components of a computer system (such as PCs, minicomputers and mainframes) may be divided into two functional units—the computing system 102 and the human interface (or “HI”) to the computing system. For a PC (Person Computer), the computing system may be the CPU, memory, hard drive, power supply and similar components. The computing system may be comprised in a chassis which holds the motherboard, power supply, hard drive and the like. The human interface, on the other hand, may comprise those devices that humans use to transfer information to and/or receive information from the computing system. The most commonly recognized devices which form part of the human interface with the computing system include the monitor, keyboard, mouse and printer. The human interface may comprise a variety of other devices, such as a joystick, trackball, touchpad, microphone, speakers, and telephone, as well as other devices too numerous to specifically mention.
In current computer systems, e.g., current PC architectures, the human interface (e.g., the display monitor, mouse, and keyboard, etc.) is closely located to the computer system, by a distance typically less than about 10 feet. The computing system 102 generates and/or receives human interface signals, e.g., display monitor, mouse and keyboard formatted data, that are provided directly to/from the human interface 130 or desktop via individual specialized cables as illustrated in prior art FIG. 1A. For example, for most PCs installed at workstations, the computer monitor 116, keyboard 112 and mouse 114 rest on the desktop while the computer chassis which holds the computing system 102 rests on the floor underneath the desktop. Prior art FIG. 1B is a block diagram of the computer system illustrated in FIG. 1A. As indicated in FIG. 1B, the computing system 102 typically includes a processor 106, i.e., a CPU, a memory 104, and I/O interface logic, such as a video card 136 and an I/O interface card 137 which are coupled to the processor 106 through an I/O bus 124. The computing system 102 also typically includes chip set logic 108 for interfacing the processor 106 and memory 104 with the I/O bus 124. As is well known, two or more computing systems 102 may be connected together in a network configuration.
Many commercial businesses and enterprises make extensive use of personal computers (PCs) in their daily operations. Typically, each user of a personal computer in the enterprise has a networked PC at their desk or work area. As the number of networked computer systems utilized in an enterprise increases, the management of such resources becomes increasingly complex and expensive. Some of the manageability issues involved in maintaining a large number of networked computer systems include ease of installation and deployment, the topology and physical logistics of the network, asset management, scalability (the cost and effort involved in increasing the number of units), troubleshooting network or unit problems, support costs, software tracking and management, as well as the simple issue of physical space, be it floor space or room on the desktop. In addition, there are security issues regarding physical assets, data protection, and software control. In many business establishments, such as call centers, there is no need for the user to install software on his/her unit, and in fact, management may specifically forbid employees from doing so. However, the standard personal computer configuration inherently provides the user this ability because the system is typically located with the user, and includes a floppy drive, CDROM, and one or more hard drives. Ensuring that unauthorized software is not installed on any of the machines in the network involves periodically personally auditing the software contents of each machine, at substantial cost in time and effort.
In order to fully resolve the aforementioned issues, in some current systems the entire computing system is physically separated from the human interface, specifically, by keeping the human interface (monitor, keyboard, mouse and printer) at the desktop or workstation while relocating the associated computing system (motherboard, power supply, memory, disk drives, etc.) to a secured computer room where plural computing systems are maintained. By securing the computing systems in one room, the employer's control over the computer systems is greatly enhanced. For example, since employees no longer have personal access, through the floppy or CD drive, to the memory subsystem, employees can not surreptitiously remove information from their computing system. Nor can the employee independently load software or other data files onto their computing system. Similarly, the employee can no longer physically change settings or otherwise modify the hardware portion of the computer. Maintenance is also greatly facilitated by placement of all of the computing systems in a common room. For example, the repair technicians and their equipment can be stationed in the same room with all of the computing systems. Thus, a technician could replace failed components or even swap out the entire unit without making repeated trips to the location of the malfunctioning machine. Such a room can be provided with special HVAC and power systems to ensure that the room is kept clean, cool and fully powered.
U.S. Pat. No. 6,012,101 titled “Computer Network Having Commonly Located Computer Systems”; U.S. Pat. No. 6,119,146 titled “Computer Network Having Multiple Remotely Located Human Interfaces Sharing a Common Computing System”; U.S. Pat. No. 6,038,616 titled “Computer System With Remotely Located Interface Where Signals are Encoded at the Computer System, Transferred Through a 4-wire Cable, and Decoded at the Interface” disclose systems where a plurality of computing systems are located at one location, and the human interfaces associated with these computing systems are remotely located at respective desktops.
FIG. 2 illustrates an exemplary prior art system where the human interface is remotely located from the computing system. The system of FIG. 2 includes a computing system, an upstream encoder, a communication medium, a downstream decoder, and the human interface devices. The downstream decoder and the human interface devices are located remotely from the upstream encoder and the computing system. This system employs a protocol wherein human interface signals generated by the computing system are encoded by the upstream encoder into a format which allows transmission over a lengthy distance to the remote location where the human interface devices are located. The encoded signals are then transmitted over the communication medium. The encoded human interface signals are received and decoded by the downstream decoder at the remote location, being converted back into the originally generated human interface signals for propagation to the human interface devices. Human interface signals generated by the human interface devices are similarly encoded by the downstream decoder, transmitted over the communication medium, decoded by the upstream encoder, and provided to the computing system. Thus, to date the separation of the computing system from the human interface has involved extension of the human interface signals, (monitor, mouse, keyboard, USB (Universal Serial Bus) and other I/O signals), i.e., extensions of already existing I/O signals, that is, the human interface signals are generated by the computer (or human interface device), are changed or reformatted as needed for transmission to a distant or remote location, and then converted back to their original format.
In some enterprises, multiple channels or sources of information may be monitored by a user, such as, for example, telephone, television, video conferencing, audio, and/or web browser, among others. However, prior art systems which attempt to integrate such disparate forms of information for presentation to the user, e.g., over an Ethernet network, are unable to satisfactorily do so because of a number of issues. These issues include one or more of bandwidth, protocol and hardware incompatibilities, and limited computation resources, among others.
For example, one approach for delivering video content to the desktop, e.g., television content, includes installing a cable television (CTVA) system at the desktop, including either putting a television set at the desktop or installing a TV card in the computer. However, CTVA systems generally require a complete independent wiring network to each desktop which includes power splitters, line amplifiers, heavy cabling, and a master translator/re-modulator as a head end source. This network can be quite expensive, unsightly, heavy, and limited in the kinds of sources that can be fed over the system. In addition a TV set may be required which takes up valuable space and power and may generate substantial heat. In the case of a TV card being added to the desktop personal computer, the associated hardware places an additional load on the computer's performance, degrading its ability to function as a computer for the purposes of the business.
Another approach for delivering video content to the desktop involves conversion of streaming video information into packet based network data (e.g., Ethernet packets), and displaying the video using the computer system as a television set. However, using the Ethernet network as a conduit for the content video has the dual degrading effects of loading the network with non-computer data and, as above, tying up the computer's computation resources with non-computer-related tasks.
Furthermore, in returning information from the user's desktop (human interface or HI), prior art methods have typically either used a second cable or USB to carry all the return information. A primary disadvantage of deployment of the second cable is that standard enterprise desktop installations today typically already have a Category 5, 6, or 7 communications cable connecting the desktop (the HI) to a ‘back room’ where the return signals are destined. This second cable adds considerable cost in labor to the deployment of the computer system, and effectively doubles the amount of space needed for the cabling. A primary disadvantage of the use of USB to carry the return information is that USB signaling for video and audio generally introduces considerable, and quite objectionable, delay or latency into the signals. Typically such video and audio signals lack synchronization between lip movements and the corresponding spoken words, resulting in low and usually unacceptable quality. In addition, at USB frame-rates, the image stream takes on a ‘sequence of photos’ perception rather than a smooth and continuously flowing character.
Therefore, improved systems and methods are desired for adding content and/or communication distribution functionality to co-located computer systems, such as in a videoconferencing system.